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rosemary frostweed

hoary frostweed, plains frostweed

Habit Herbs. Herbs.
Stems

ascending to erect, (13–)20–40(–51) cm, stellate-tomentose.

erect, clustered on vertical caudex, (12–)20–50(–67) cm, simple or branched, stellate-pubescent to stellate-tomentose.

Leaves

cauline and, sometimes, basal basal mat-forming;

petiole 1–3 mm;

blade obovate, 10–22 × 3–5 mm;

cauline: petiole 1–4 mm;

blade oblanceolate to narrowly lanceolate, 10–38(–48) × 2–5.5(–7.8) mm, margins revolute;

surfaces stellate-tomentose abaxially, stellate-pubescent adaxially, without simple hairs;

lateral veins obscure abaxially.

cauline;

petiole 1–4 mm;

blade narrowly elliptic to oblanceolate, (10–)18–32(–40) × 4–7(–10) mm, surfaces stellate-tomentose abaxially, stellate-pubescent adaxially, without simple hairs, lateral veins raised abaxially.

Inflorescences

axillary and terminal, solitary flowers or glomerules; chasmogamous flowers solitary, at tips of branches, overtopping cleistogamous, cleistogamous 2–7 per glomerule, flowering 1–3 months later than chasmogamous.

terminal, cymes; chasmogamous flowers 6–10(–18) per cyme; cleistogamous in glomerules, 1–10 flowers per glomerule, on lateral leafy branches 2.5–6 cm, flowering 1–3 months later than chasmogamous.

Pedicels

10–22 mm;

bracts 3–7 × 0.5–1 mm.

(1.5–)3–8(–12) mm;

bracts 3–7 × 0.5–1 mm.

Chasmogamous

flowers: outer sepals linear, 1.2–2.5 × 0.2 mm, inner sepals 2.5–4.3 × 1.3–2 mm, apex acute;

petals obovate, 4–6 × 3.5–5 mm;

capsules 2–3 × 1.4–1.8 mm, glabrous.

flowers: outer sepals linear, 3.5–4.5(–8) × 0.4–1 mm, inner sepals ovate-elliptic, 5–8 × 2.4–4 mm, apex acute;

petals obovate, 8–12 × 5–10 mm;

capsules 3–5.5 × 2.5–4.5 mm, glabrous.

Cleistogamous

flowers: outer sepals linear, 0.5–1 × 0.2 mm, inner sepals ovate, 1.5–1.8 × 1–1.5 mm, apex acute;

capsules 1.3–1.7 × 1–1.3 mm, glabrous.

flowers: outer sepals linear, 0.5–1.5 × 0.3 mm, inner sepals ovate-elliptic, 1.7–2.8 × 1.5–2.3 mm, apex acute capsules 1.5–2.2 × 1.2–2.2 mm, glabrous.

Crocanthemum rosmarinifolium

Crocanthemum bicknellii

Phenology Flowering May–Jul. Flowering Jun–Jul.
Habitat Dry, sandy roadsides, openings in pine and pine-oak woodlands, disturbed soil of clearings and fields Sandy or rocky barrens, glades, sandhills, prairies, fields, pine-oak woodlands, oak-hickory woodlands, montane outcrops and balds
Elevation 0–200 m (0–700 ft) 0–1500 m (0–4900 ft)
Distribution
from FNA
AL; AR; FL; GA; LA; MS; NC; OK; SC; TX; West Indies (Dominican Republic)
[BONAP county map]
from FNA
AR; CO; CT; DE; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; NC; NE; NH; NJ; NY; OH; PA; RI; SC; SD; TN; VA; VT; WI; WV; WY; MB; ON
[BONAP county map]
Discussion

Crocanthemum rosmarinifolium is easily distinguished from sympatric species by its slender leaves, relatively small petaliferous flowers, occasional basal leaves, and overall pale color. As noted by R. M. Harper over a century ago, it seems not to occupy natural habitats and is found primarily on roadsides. Populations in the Dominican Republic occur up to at least 2200 m.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The dense, often crowded, cleistogamous flowers on branches of Crocanthemum bicknellii late in the season

contrast strongly with the relatively few, terminal, petaliferous flowers early in the season. Its closest relative is 12. C. propinquum; see that treatment for identification aids. The names C. majus (Linnaeus) Britton and Helianthemum majus (Linnaeus) Bicknell have been misapplied to C. bicknellii. They were based on Lechea major Linnaeus, which is a synonym of C. canadense, based on types.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 407. FNA vol. 6, p. 402.
Parent taxa Cistaceae > Crocanthemum Cistaceae > Crocanthemum
Sibling taxa
C. aldersonii, C. arenicola, C. bicknellii, C. canadense, C. carolinianum, C. corymbosum, C. dumosum, C. georgianum, C. glomeratum, C. greenei, C. nashii, C. propinquum, C. scoparium, C. suffrutescens
C. aldersonii, C. arenicola, C. canadense, C. carolinianum, C. corymbosum, C. dumosum, C. georgianum, C. glomeratum, C. greenei, C. nashii, C. propinquum, C. rosmarinifolium, C. scoparium, C. suffrutescens
Synonyms Helianthemum rosmarinifolium, C. domingense, C. stenophyllum Helianthemum bicknellii, H. canadense var. walkerae
Name authority (Pursh) Janchen: in H. G. A. Engler et al., Nat. Pflanzenfam. ed. 2, 21: 307. (1925) (Fernald) Janchen: in H. G. A. Engler et al., Nat. Pflanzenfam. ed. 2, 21: 307. (1925)
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